1. You know how fast your boat is. Check the predicted currents in Eldredge, online http://www.mobilegeographics.com:81/locations/2495.html
, or on your chartplotter. I have had to wait for the lift bridge on the east side of Roosevelt on several occassions and never had a problem maintaining position on a variety of sailboats.
2. I have never experienced any significant steering problems in strong currents. My most recent rips through was on a Colgate 26; we didn't get bounced around much. Pay attention and you'll see the whirpools even at night. Although it's fun to pass the cars on the FDR, select a point in the current cycle when the current is milder if you're apprehensive.
3. Whether or not the west channel is closed depends upon the prevailing security concerns. The two most recent times that I transited the East River the West Channel was closed because Mahmoud Ahmadinejad was speaking at the UN. Most of the time he's raising hell in in Iran not the UN.
I reiterate it's a beautiful trip. I always enjoy it you should too.